Because the Sabre is an 8-channel part, today's standalone converters run dual-differential circuit topologies with paralleled DACs. There are two DACs per phase per channel (8 total) whereby each of those 8 DACs is fully balanced unto itself. This
configuration allows for better than 132dB of dynamic range.
On clock recovery, "the S/PDIF interface is more complex than the DSD and I²S
since it must first derive the embedded clock in the bi-phase
encoded data. In fact, experience with many forms of S/PDIF
decoders suggest that most fail in the presence of high jitter due
to the lack of robustness in the clock recovery process. To
avoid this potential problem, the Sabre S/PDIF interface avoids
having to extract the clock at all. Decoding is done using a
method that does not require an explicit measure of the clock
frequency.

"Specifically, the digital input is first corrected for 50% duty cycle by means of a discrete digital delay line that is
able to delay either the positive edge or the negative edge of
the signal such that after this delay line the signal is at 50%
duty cycle. Thereafter an assessment is made of the width of
each pulse based on its relation to recently seen pulse widths
and a decision circuit assigns each a width of 1, 2 or 3 units.
A state machine then operates on the assigned widths in
succession. This state machine is searching for the block
boundaries and the bit states. The state machine makes no
attempt to re-time or otherwise decode the clock – it simply
time stamps the event and passes it to the downstream
processor. Using this method, the S/PDIF interface is able to
accommodate 50nS of random jitter and 200nS of sinusoidal
jitter in the incoming data."

On DSP frequencies, "the Sabre DAC operates at either 27MHz for audio
rates up to 96KS/s or 40MHz for audio data rates up to 192KS/s. Neither of
these rates is integer-related to the audio clock." This Sidebar has more technical info.

Only the DAC2 gets an I²S balanced input over HDMI, the extra AES/EBU digital input and a DC-triggered HT bypass. Both run two coaxial and two optical inputs and XLR and RCA analog outs. Only the DAC2 gets the 32-bit on-chip digital volume control enabled and a remote wand. It also upgrades the LCD to a VDE readout. That displays not just input and sampling options like the DAC1 but the bypassable variable output level. Both use the same oversized toroidal power transformer.

Ditto a 35A bridge-rectified power supply with 88.000uF filtering. The DAC2 upgrades to W4S's proprietary low-ESR 'super caps' like the SE preamp and Schottky bridge rectifiers. Welcome EJ Sarmento's new D/A converter under the Wyred4Sound brand. Its two-tier pricing suggests high value even with the bling version. That would be tradition by now. EJ and glam don't rhyme. Ejay is okay does.

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* The USB 1.1 spec is limited to 24/96. USB 2.0 is currently exclusive to OSX where it supports 24/210. To offer a 24/192 capable USB DAC, a company must write or license firm ware (a special device driver as is necessary also for FireWire).

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Sarmento's reviewed and awarded $2.000 STP-SE preamp above featured performance equivalent to the $10.000 Esoteric C-03, albeit not the latter's variable gain structure, vault-type enclosure or fancy remote. It thus became Frederic Beudot's chosen poison and Joël Chevassus on staff acquired his own. Mr. Sarmento is no stranger to our team. Had the company been called EJ Audio, his name would be more widely known already. As is, Wyred4Sound suggests a garage band, not serious hifi player. Some might think that wyred is Welsh for weird in fact. But without steep hifi stickers, all is well.
Having launched Wyred with ICEpower amps, EJ's true design chops came to the fore with his carte blanche preamp. The integrated which followed applied portions of the preamp and grafted them atop B&O's turnkey boards. The converter began as a tabula rasa again. Dual-differential signal paths were a must as were upgradeable (modular) i/o boards for future proofiness. The chassis would copy what came before - solid but not overbuilt and without a costly half-inch trophy plate. Dress code is silver or black and international voltage preconfigured.

The 24/192 USB club has few members right now. The super-cheap M2Tech hiFace is one, Antelope Audio's Zodiac+ another as are Musiland and Audiophilleo. Soon there'll be many. For now add Wyred. Ditto for async USB for home audio. Wavelength, Ayre, dCS, Resolution Audio's new Cantata, all the HRT Streamers, the Analog Research Tech Legato and now Wyred4Sound are a few.

"The 24/192 USB interface does require a dedicated device driver to properly enable the device. We use our proprietary microchip-based driver which is also Microsoft signed 'verified' to pose no issue with 64-bit platforms." The I²S-over-HDMI feature seems predestined for PS Audio's PerfectWave transport. That's a natural. Wyred4Sound's business home of Cullen Circuits used to assemble PS Audio machines before Paul McGowan turned to the PRC for outsourcing and essentially created the conditions which would force EJ Sarmento and partner Rick Cullen to set up shop as competitors. Because those two modified between 500 to 600 of PS Audio's Link DAC 3s, they're already very experienced when it comes to optimizing digital.

There's further talk of Cullen Circuits modifying existing transports to add the HDMI/I²S port. On Wyred's pricing, consider Ayre's QB-9. It's $2.500 and the current press darling in USB land. But that's all it does, USB. The DAC2 is $1.000 less and a full-featured DAC/preamp with every digital input in the book. That's strategic if not aggressive. Economic leanness ain't all bad. Many makers tighten belts just to retain market share. Wyred is a newer player with no entrenched reputation yet. Today high value hits heavier than ever. Here the DAC1 and 2 hit hard. Ken Micallef will weigh in on the DAC1 to assess how value translates to performance.